Configure the taskbar in Windows 7

Control thumbnail preview

When hovering the mouse over an application in the taskbar, then it will display a small thumbnail image of the application window.

Create this DWORD key to control the delay before showing the thumbnail:

[HKEY_CURRENT_USER \Software \Microsoft \Windows \CurrentVersion \Explorer \Advanced]
ThumbnailLivePreviewHoverTime = 50 (Time in miliseconds)

Note by setting it to a very high value, then it will seem like the application thumbnail is disabled.

Control live preview

When hovering the mouse over an application in the taskbar then it will display a live preview of the whole window (Aka. Aero Peek).

Create this DWORD key to control the delay before showing the live preview:

[HKEY_CURRENT_USER \Software \Microsoft \Windows \CurrentVersion \Explorer \Advanced]
ExtendedUIHoverTime = 200 (Time in miliseconds - Default 400 ms)

Note by setting it to a very high value, then it will seem like the application preview is disabled.

Credits WinGeek.com